(gdb) bt
#0  proxy_worker_cmp (a=0x7ffb18002438, b=0x7ffb18002470) at mod_proxy_cluster.c:154
#1  0x00007ffba4c87ba3 in msort_with_tmp (p=0x7ffb551b37f0, b=0x7ffb551b3748, n=2) at msort.c:124
#2  0x00007ffba4c87b02 in msort_with_tmp (n=2, b=0x7ffb551b3748, p=0x7ffb551b37f0) at msort.c:45
#3  msort_with_tmp (p=0x7ffb551b37f0, b=0x7ffb551b3748, n=5) at msort.c:53
#4  0x00007ffba4c87ef7 in msort_with_tmp (n=5, b=<optimized out>, p=0x7ffb551b37f0) at msort.c:45
#5  __GI___qsort_r (b=b@entry=0x7ffb18002438, n=n@entry=5, s=s@entry=56, cmp=cmp@entry=0x7ffb90ae5e00 <proxy_worker_cmp>, arg=arg@entry=0x0) at msort.c:254
#6  0x00007ffba4c88148 in __GI_qsort (b=b@entry=0x7ffb18002438, n=n@entry=5, s=s@entry=56, cmp=cmp@entry=0x7ffb90ae5e00 <proxy_worker_cmp>) at msort.c:308
#7  0x00007ffb90ae9ae7 in internal_find_best_byrequests (conf=0x55fe55cacb88, node_table=0x7ffb180108e0, context_table=0x7ffb1800fed8, 
    vhost_table=0x7ffb1802baa0, failoverdomain=0, domain=0x0, r=0x7ffb18006a10, balancer=0x55fe56065140) at mod_proxy_cluster.c:2331
#8  find_best_worker (balancer=0x55fe56065140, conf=conf@entry=0x55fe55cacb88, r=r@entry=0x7ffb18006a10, domain=domain@entry=0x0, 
    failoverdomain=failoverdomain@entry=0, vhost_table=vhost_table@entry=0x7ffb1802baa0, context_table=context_table@entry=0x7ffb1800fed8, 
    node_table=node_table@entry=0x7ffb180108e0, recurse=recurse@entry=1) at mod_proxy_cluster.c:3484
#9  0x00007ffb90aed611 in proxy_cluster_pre_request (worker=0x7ffb551b3b38, balancer=0x7ffb551b3b30, r=0x7ffb18006a10, conf=0x55fe55cacb88, 
    url=0x7ffb551b3b40) at mod_proxy_cluster.c:3851
#10 0x00007ffb9a409fa6 in proxy_run_pre_request () from /usr/jboss/jbossweb/shopapp_ws_m01/modules/mod_proxy.so
#11 0x00007ffb9a40ec62 in ap_proxy_pre_request () from /usr/jboss/jbossweb/shopapp_ws_m01/modules/mod_proxy.so
#12 0x00007ffb9a40a7dc in proxy_handler () from /usr/jboss/jbossweb/shopapp_ws_m01/modules/mod_proxy.so
...

(gdb) disassemble 
Dump of assembler code for function proxy_worker_cmp:
   0x00007ffb90ae5e00 <+0>:     mov    (%rdi),%rax
=> 0x00007ffb90ae5e03 <+3>:     mov    0x18(%rax),%rdi
(gdb) info registers rax
rax            0x9e10fcde4a34ed64       -7056862584431645340
(gdb) x 0x9e10fcde4a34ed64
0x9e10fcde4a34ed64:     Cannot access memory at address 0x9e10fcde4a34ed64
(gdb)